This topic will contain images & discussion of same as they arrive during the extended download period. Similar threads will be opened in coming months as required as acquired data & discussion proceeds.

User torque_xtr (http://www.astronomy.ru/forum/index.php?action=profile;u=28931) proposed the idea that Sputnik Planum is basin filled from the atmosphere by nitrogen. In this regard, I simulate the amount of heat obtaned by Pluto from sun irradiation.
For a start I make the map, in which replaced the central part of unexplored region near the south pole into Sputnik Planum vicinity, so you can see how much energy is absorbed bright and dark areas near the south pole.
Figure shows amount of energy absorbed by surface of Pluto in one turn around the Sun.
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Colour picture shows the solar irradiation in the projection relative to the rotation axis of Pluto.
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Next pictures was made in projection relative the axis perpendicular both to the rotation axis and direction of Charon:
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At the center of second projection is a south pole, the north pole is on the left and right edge of the picture, the upper and lower edge are equatorial points with longitude 90° and 270°.
Due to the large inclination of the rotation axis of Pluto to the orbital plane, Pluto's polar regions on average much hotter then equatorial region, so that in contrast to the Earth and Mars "polar cap" have to look at the equator. Minimum insolation during the plutonian year gives 1.703 gigajoules per square meter, the maximum - gives 1.952 GJ/m^2.
Area Tombaugh absorbs a minimal amount of solar energy over the entire all surface of the planet. If it is assumed that the emissivity in the far infrared range varies less than in the optical range, Sputnik Planum would be cooler in which there is a continuous deposition of gases from the atmosphere occure. And this process is the driven force for glacier flow.

Excuse me, is there somewhere information about exposures of LORRI and MVIC images of Pluto from the night side? It will be seen night side of Pluto surface in Charonshine?

There are images (yet to be downlinked) of Pluto lit by Charon, and the central area lit would be near latitude 0 / longitude 0

Interesting to note minimum insolation at the equator over the course of a Plutonian year. Does the tilt of Pluto's axis vary over geological time scales? I'm wondering why the deepest blue in your upper Pluto color image (area of minimum absorbed solar radiation) seems longitudinally offset from Tombaugh Regio?

Color pictures give density of irradiated solar energy, not absorbed solar radiation. Density of absorbed energy are shown in black-and-white pictures (it is simple multiplication of irradiated density by (1-albedo)). The variation of color along the equator has a numerical nature, and the real variation due to solar eclipses significantly less.
Next picture shows eclipse term.
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Source of variation in previous version of pictures was non-constant time step of integration (the algorithm decrease time step during solar eclipse by Charon) and fractional turns of Pluto around it axis in one orbital period.
Now these shortcomings are eliminated.
The radiation can be considered constant along the equator, and the formation of the Tombaugh Regio can be explained by large impact feature, which was the seed for the condensation of gas (due to opened lighter surface). The presence of the "equatorial cap", together with the formation of impact has led to a redistribution of the masses, so that the pendulum has swung Pluto along the line passing through the center of the masses of Pluto and Charon.

In Pluto's north, there are these dark smudges (native res and enlarged) that I wonder if could be geysers or geyser remnants:


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Further north (I think..) is another smudge (and an apparent linear feature next to it, thrown in for good measure):

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(between them sits this obvious smudge feature, but it looks somewhat unrelated)

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One can find other similar features in the area.

Further south, we do of course also have all these smudges in Burney crater:

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One of them clearly looks like it has a tail:

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Then there are those other numerous things with dark centres and bright haloes

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they look like craters, but their distribution is a bit odd (there are what looks like a bit like tail features (streaks) in picture above, also). Most of them look relatively spherical, but some might be more irregular in shape:

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There are also these really messy areas (not far from the previous feature) that could be related:

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For comparison, here are some dark smudges in the geyser region of Triton:

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Yes.
...

--Bill

Another interesting feature of relief: small dimples. I suppose that it is an analogue of the dunes in the desert, caused not by the wind but solar irradiation conditions.
Oriented to the Sun the north side evaporates and on the shady south sides condensation occurs. Thus, the instability of a flat surface develops and slowly creeping dunes to the south (when in the northern hemisphere is summer). Therefore, the perpendicular meridians orientation of formations can be observed.

Maybe an additional assumption of a circular orbit would help provide a useful analytical expression to help picture this?

I expect Pluto's axis of rotation to be very stable because of the gyroscopic effect of Charon in the Pluto-Charon system. Also, the resonant orbital behavior with respect to Neptune should be stable.

Note that Europa has an icy crust which is decoupled from its interior and rotates very slowly, at a rate that has not been established, with respect to Europa's interior. I don't know if that possibility exists for Pluto or Charon.

That would help and could easily be added in later.


Possible. Without a significant interior heat source to actually melt an icy mantle, at-depth and away from STP (Std Temp Press), the various ices (water plus whatever else) and gases could make a high-viscosity flow which could decouple crust+mantle over geological time frames. At first look Pluto's surface looks smooth and flexy and may well be mobile at-depth, but Charon, with the Mordor region crater and the equatorial Chasmas would seem to be cold, frozen and solid.

IMO.

--Bill

I don't think the surface is decoupled from the interior here, though I'd like to be wrong.

There is no evidence either way, but I don't think so either. 'Tis a possibility.

"Pluto’s insolation history: Latitudinal variations and effects on atmospheric pressure" by Earle and Binzel in April's edition of Icarus is probably the last word on Pluto's insolation history. They've done all the calculus so we don't have to!
For those without access there are various papers on Arxiv which touch on the subject.

Yes! I'm planning to read that once I get into town to the Library.

It is the last word as of April, but I'm sure that there will be many other words post-encounter.

--Bill

I check LORRI trajectories in the NASA's Eyes software and conclude to my big regret, that all post-encounter frames was taken at the limb area and have exposure about 0.1 s, but not at least 10 s which neсessary to obtaining a good night side picture... I'm wrong?

I read somewhere that the Charonshine images of Pluto would be MVIC images near close approach and LORRI images at a distance where Pluto would fill most of the frame. Also the LORRI images would be many short images which would be added, this will allow them to avoid smearing of the images and bleeding from the overexposed parts of the images.

Checking the orbital positions, there were Charonshine opportunities for imaging Pluto on July 14, July 20, etc. and Plutoshine opportunities for imaging Charon on July 17, July 23, etc.

If we get some regional albedo information for the mid-southern latitudes, that would be great. A bonus would be if we get some details and/or could see if Charon has a dark region at the other pole, too. I'd love to see something like the Saturnshine images of Iapetus, but I'm not getting my hopes up.

If my memory serves me right, long-exposure 4x4 binned images should have been taken for this purpose. I thought, this has been hinted at in one of the press conferences. We'll know for sure before the end of the year, after the browser images will be downlinked.

Alan, Gerald, thank you very much for this encouraging information about night side pictures!!!
Once again I watch my animation of New Horizons FlyBy
https://www.youtube.com/watch?v=GYpw4joQPzo
trying to imagine how those will look like night shots :-)

I believe these are the MVIC and LORRI Charonshine images listed in the New Horizon's Full Activity List

According to Solar System Simulator, Charon was at half phase as seen from Pluto during those images, and decreasing with passing time. So those should be Charonshine images – not the best lit, but good resolution. It seems like several hours earlier would have been a better opportunity, but perhaps the thin daylit crescent of Pluto would have been a problem at that time.

So roughly half of Pluto in Charonshine then.

All of Pluto's Charon-side in the light of a half Charon.

The portion of Pluto facing Charon never changes, so there's no variation in that regard whatsoever. At any point in time that Charon isn't "new" as seen from Pluto, that entire half of Pluto will get some Charonshine. Only the quantity of illumination will vary, not the areas on Pluto that are illuminated.

A key part of this point is that half of the night side of Pluto will be illuminated by Charon.

Another point to consider: since the illumination is coming largely from the northern hemisphere of the reflecting body, it will be barely able to illuminate the south pole itself. And the bodies are pretty close to each other. Imagine you are at Pluto's south pole - can you see Charon at all? Or is it below the horizon, as Phobos and Deimos are from Mars's poles? In fact it will be below the horizon out to a certain distance from the pole, and for an additional distance, only the night side of Charon would be above the horizon, so not illuminating anything. It's intriguing to speculate on the appearance of Pluto from Charon's south pole - in some range of latitudes Pluto's night side would be above the horizon, its illuminated portion still below the horizon, but arcs of faintly lit atmospheric haze might reach up from the horizon as we saw in the backlit view. They might not make a full circle because of the geometry.

As for the range of longitudes, as the system rotates the illuminated night half will sometimes be better placed for viewing, sometimes less so. Light bleed from the sunlit crescent will be a problem, so when the Charonshine region is adjacent to the sunlit crescent we should have better viewing geometry but worse light pollution. When it's opposite the sunlit crescent it will be foreshortened but less contaminated. So a lot depends on the timing of imaging. I would like to see some simulations of this.

Phil

A half-phase Pluto should be illuminated by a half-phase Charon, according to what was said about the Solar System Simulator model.

With the Earth-Moon duo, the phase of the Earth, seen from the Moon, is an inverse-mirror. A Crescent Moon, it "sees" a Gibbous Earth, and a Gibbous Moon sees a Crescent Earth. On our Moon, First or Last Quarter Earthshine is quite dim, and is somewhat overwhelmed by the illuminated half of the Moon. It may show something but my expectations are not high.

--Bill

All the posters here clearly understand the geometry but not all visitors will. Can anyone provide a simple diagram for the Charonshine imaging showing which parts of the 'planet' will and won't be seen?

One could take a map like the ones we already have and outline the Charon-facing hemisphere on it too. That would show exactly how much of the southern hemisphere could be illuminated/imaged.

Yes the approximate region on the Pluto maps would be between -90 and +90 longitude. On my map (centered on 180 longitude) this would be within 90 degrees of the left and right edges, or the left quarter and the right quarter. The latitude range as Phil pointed out would be not quite all the way to the poles, related to how many Pluto radii Charon lies at. It would be interesting to map this out in terms of the illumination, being proportional to the sine of Charon's angular altitude from each point on Pluto's surface. This altitude reaches a maximum at the zenith at latitude 0 longitude 0.

We could also import a Pluto map into Celestia, position the observer near Charon (on its Pluto facing side) and take a look at what portions of Pluto show up. This Charon illuminated portion will be fixed as a function of time, even though the sunlit phases of Pluto and Charon will vary. Meng-'Po Macula is at the best location.

Assuming that the information above is correct, the illumination for the two observations listed above would be like this:

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The upper image (the one simulating the MVIC geometry) has a FOV of 10 degrees and the lower one a FOV of 0.2907 degrees (the LORRI FOV).

I made no attempts to make the brightness of the Charonshine areas correct relative to the bright sunlit limb. These test renders are primarily intended to approximate which areas are in Charonshine. Charon is modeled as a point source but that doesn't make a big difference (in reality the illuminated area should be slightly bigger).

With the use of map
http://www.unmannedspaceflight.com/uploads...19373_thumb.png
I simulate the frame
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x632_sci_3.jpg
and got a picture
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(To comparision the original frame are placed in the last right and difference between the original and the simulated image can be seen on an middle picture)
There is some distortion of the image is apparently due to the different definitions of the rotation axis and the longitude, as well as slight map distortion.



Also I plan to simulate other LORRI and MVIC frames (include Charonshine frames)...

I have been experimenting with generating DEMs of Pluto from stereo imagery, mainly to see if there are any large scale elevation differences (e.g. from subtle impact basins). The images available so far aren't exactly optimal for this and also my stereo match software is very sensitive to compression artifacts.

So far I have tried two stereo pairs:
lor_0299174713_0x632_sci_5.jpg and lor_0299148167_0x632_sci_3.jpg
lor_0299175145_0x632_sci_7.jpg and lor_0299148167_0x632_sci_3.jpg (again)

These pairs are far fram optimal since the resolution of lor_0299148167_0x632_sci_3.jpg isn't high and the resolution difference between the images is large (differs by a factor of ~6). Sputnik Planum is also almost featureless in the lower-res image, making it difficult to find matching features. The resulting DEM is noisy and too ugly to post here but at least there is one possible result: Sputnik Planum is *probably* not a depression, its elevation is *probably* comparable to the elevation of the surrounding, dark terrain (if Sputnik Planum is despite this really a depression it would probably be a very gentle depression, much more so than big craters and basins on e.g. Rhea). But I want to emphasize the word "probably" in everything here - the DEM is noisy and of low quality.

I also experimented with the lor_0299148167_0x632_sci_3.jpg / lor_0299124574_0x632_sci_1.jpg pair but without any useful results. The resolution is too low and compression artifacts mess things up.

By the way, one of the most interesting features I noticed when I was doing the DEM work was this in image lor_0299174713_0x632_sci_5.jpg, slightly sharpened here:

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Here the stuff in Sputnik Planum has apparently been flowing into a crater. This reminds me of terrestrial glaciers - seeing higher-res images of Sputnik Planum's edge is going to be really interesting.

Of course the vast majority of the really interesting (i.e. hi-res) images are still aboard the spacecraft. As interesting and exciting as everything has been so far, the real fun really doesn't start until September when downlinking of the imaging data starts.

Can't wait to see the topgraphy!

Does it appear to anybody else that the hill-ice field boundary appears like the N2 ice is dissolving the rough terrain, not flowing over it?
E.g., the dark swirls look like chocolate terrain dissolving into the milky N2 ices?

The flow patters seem more like dark material being drawn into the lighter colored ice field, not like white ice advancing over a dark terrain.
If liquid phases of N2 are stable a few meters down, you'd have a glacier that "skated" on the liquid layer and also dissolved the surrounding terrain.

There should be some very interesting "geology" err, "iceology" here, solid solutions, eutectic solutions might create icy analogs of sedimentary or igneous rocks.
Grains of different ices held together in a matrix of another ice or mixture of ice.

The dark swirls may be due to grain size changes, or areas of transparent ice. When we are looking at nitrogen ice, carbon monoxide ice and so on, it's very difficult to know what would dissolve in what, so I prefer a physical explanation at the moment.

Phil

Agreed, Phil. These wide-view images don't provide nearly enough detail to understand what's going on at the process/mechanism level yet. Hopefully there will be clues worthy of hypothesis formation found in the most detailed pics yet to come.

Speaking of ices, glaciers, flow patterns etc., a lot of examples of how terrestrial glaciers can appear can be seen in a big mosaic I did a few years ago of southern Greenland from Landsat 7 images: http://www.planetary.org/blogs/guest-blogs...nd-jonsson.html

There appear to be some superficial similarities but it must be kept in mind that the resolution of the Pluto images is much lower (the resolution of the Landsat mosaic is ~30 m/pixel).

I'm not yet convinced there is flowing ice here. Light and dark dust being wafted around in the thin air seems more likely.

I'm not either - as I mentioned above, the resolution of the Pluto images really isn't very high yet. The highest-res images will be really interesting, plus surface composition measurements (LEISA data).

Has anybody done a montage of similar scale / resolution images of ice features?
Say, Tombaugh with 20 mile size bar, then Enceledaus, then Europa, then Martian chaos terrain, then Earth arctic?

Idea being, even with physical chemistry that is fundamentally different, Titan has features which are recognizable,
presumably because the materials are different, but the math and the patterns remain the same.

That shouldn't be possible. N2 requires a minimum of around 15-20 meters of ice at Pluto's pressure and gravity at an optimal temperature. Eutectics may have a significant impact on the required temperature range, but they're unlikely to lower the pressure requirements, esp. since nitrogen has much lower pressure requirements than CO, Ne, etc.

I wouldn't be surprised if there are actual liquids there rather than just flowing solids (though the boundary between liquids and solids is kind of fuzzy in this context). But if so they're going to be a lot deeper than just a couple meters. It'd also mean that temperatures would either have to be a bit warmer than Pluto's average solar equilibrium temperature, or that eutectics would need to lower the triple point temperature. Neither are unrealistic possibilities, but there's no guarantees either - and the high albedo of Tombaugh works against it.

I really want to see closeups of the "crack" patterning on Sputnik. I'm really curious as to whether they'll appear to be something filled in by liquid. Too bad there's no radar data to be able to get an idea of surface texture... I'd love to know if there's any "cryolava pillowing" going on if liquids ever reach the surface. Then again, nitrogen may not be able to form a sturdy enough shell to form pillows - we've all seen the videos of how it behaves when it's rapidly evaporatively cooled.

Since the older surface and the "glaciers" are suggested to be both made of mainly N2 ice, might it not be better to think in terms of "lava" flow rather than "Glacial" flow. Glacial flow requires lubrication, which could be possible under the main icecap, but towards the edges the lubrication would freeze and the "glacier" analogue looks less applicable.

The Northern part of Tombaugh Regio seems to be a large impact basin, one that has been largely filled in with Carbon Monoxide ice. The Nitrogen ice making up the majority of Pluto's surface, has two allotropes, one with a hexagonal type crystal structure, the other has a cubic structure, the same as diamond. This second form only forms at high pressure. It is reasonable to propose that the rim of the crater and the basin itself, is composed of this "harder" form of Nitrogen ice and is covered in the "softer", "normal" Nitrogen and Carbon Monoxide ice. This softer ice does not have the mechanical strength to sustain the height of the crater rim and so has "slumped" in a more "plastic" flow, over the more solid layer below.

One might guess the "diamond" form of Nitrogen ice might be close to transparent too. Not sure if the Ralph or Alice data could differentiate between the two forms of Nitrogen ice, it could be very informative if they can.

The shock wave travelling through the surrounding ice could also create "ridges" of harder Nitrogen ice. G.I.'s image suggests this possibility in the area to the North West of Tombaugh (5 O'Clock in the image).

Correct, it's a few tens of meters, not just a few meters.



One early suggestion was that with a-phase and b-phase ice, you would get "phase change fronts"
moving across the surface and into the subsurface in response to changes in heat and sunlight.
I suspect that a phase change would result in a volume change, that stress could be an effective mechanism to erode the surface

There's a later paper that estimates where each form of N2 ice is stable during each orbit.
http://www.lpl.arizona.edu/~yelle/eprints/Stansberry99a.pdf
Stansberry & Yelle, “Emissivity and the Fate of Pluto's Atmosphere,” Icarus 141: 299-306, 1999

Interesting that their calculations predict a "phase cliff" about 20 years past perihelion, (roughly now)
where the southern hemisphere abruptly switches from B-ice being stable to A-ice being stable.

With the use of metadata of LORRI frames I clarify trajectory of New Horizons (error is about 0.000002 on distancies to Pluto at snapshots momens). After that it made possible to simulate all frames with subpixel accuracy. Here for example, two of these frames:
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As a bonus Pluto radius was determined: R=240.89 km * u, where 'u' is LORRI pixel size in microradians.
If we assume that the under-Charon avarage point has longitude 0°, then the map of Pluto (for example http://www.unmannedspaceflight.com/index.p...t&id=37374) is offset by 1.6 ° to the east. So I had to make such correction to map, that the image consistent with LORRI frames.
Nevertheless, clear to see that there are still quite a strong distortion in the map.

This translates to 1193.6 km, consistent with the 1185 +/- km measured by the NH team a day before the flyby (interestingly, I got a value of 1194 km km back then).

Regarding NH's trajectory, if I remember correctly the flyby didn't occur at exactly the planned time (off by some seconds but well within the required accuracy) and this makes it more tricky to use the metadata to accurately determine the viewing geometry (especially in the hi-res images) until an updated trajectory (SPICE kernels) becomes avvailable.

At first I tried to use the data from
http://ssd.jpl.nasa.gov/horizons.cgi#top
but I found that the position of NH was displaced approximately 120 seconds, so I used the least squares method (with using distances to Pluto, Charon, Nix and Hydra up to 2,000,000 km) to made a correction of 3D position (about 1,665 kilometers) and velocity vector (about 11.6 m/s) so that the simulated distances become coincide to metadata with an error of about 0.1 km.

Hi all, I rarely post, but had a question on this amazing mission for those more knowledgeable.

When I look at the excellent simulation in "Eyes", I can see that at approx 15 mins. before closest approach, Charon "sets" behind Pluto", then at 9 minutes, it rises. Eyes doesn't show any photos taken at all of these events, in fact NH doesn't appear to be pointing at anything. These would have not only made dramatic pictures, but presumably at the Charon-rise point would highlight features on the limb?

Am I missing something (probably), or would these images have been of no value?

Michael, I, too, for a long time the question arose.
As specially missed Charon set, while Pluto was carried out for all the cameras shooting Charon was behind, ahead of Charon, and its rise is also not hit in images.

Imaging this was suggested several years ago, but I don't know if it actually happened. Priority obviously had to be given to high-value science data acquisition at that time so I really doubt that made the cut.

What kind of scientific data loss can be a question if deviation on Charonset
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is 133 seconds, and at Charonrise
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just 50 seconds?
Judging by the nature of scanning at once by RALPH, LORRI and Alice, the images of Charonset and Charonrise were obtained. Just NASA's Eyes bit not exactly show the real program running by NH.
Due to the motion of Charon relative Pluto while TDI of MVIC camera Charon could slightly smeared. But this adds even natural tableau.